(1) Field of the Invention
The present invention pertains to a crank that is manually rotated to selectively lower and raise a landing gear assembly of a truck trailer. More specifically, the present invention pertains to a locking device that automatically secures the hand crank in its operative position relative to the landing gear assembly, where the locking device is easily disengaged to move the crank from its operative position to its stored position following the operation of the landing gear assembly.
(2) Description of the Related Art
Many of the different types of trailers that are towed by trucks are connected to the trucks by a releasable coupling such as a gooseneck coupling or a fifth wheel coupling. When the trailer is released from the truck and is no longer supported by the truck at the forward end of the trailer, a landing gear assembly is often used to support the trailer floor or bed in a generally horizontal position.
The typical landing gear assembly is attached to the underside of the trailer adjacent the truck coupling at the forward end of the trailer. The assembly includes a pair of vertically oriented columns positioned adjacent opposite sides of the trailer bed. A vertical leg is mounted on each column. A gear mechanism on each column is selectively operated to lower the legs from the columns, or raise the legs on the columns. The gear mechanisms of the two columns are connected by a shaft assembly that extends across the underside of the trailer between the two columns. A hand crank is connected to the shaft assembly at one side of the trailer. Selectively rotating the hand crank in opposite directions lowers the pair of legs until the legs contact the ground and support the trailer forward end when the trailer is being uncoupled from the truck, or raise the pair of legs when the trailer has been connected to a truck and is ready for towing.
The typical hand crank is connected to the shaft of the landing gear assembly by a pivot connection. The pivot connection enables the hand crank to be pivoted outwardly from a side of the trailer to an operative position of the crank where there is ample clearance to rotate the crank in selectively lowering and raising the legs of the landing gear assembly. When the trailer is being towed, the pivot connection enables the hand crank to be pivoted beneath the landing gear assembly shaft to a stored position where the crank is not projecting outwardly from the side of the trailer.
Many prior art landing gear assemblies have two speed designs that enable the legs of the landing gear assembly to be lowered and raised at different speeds. The input shaft of the landing gear assembly is moved axially inwardly and outwardly relative to the trailer to shift the assembly between the two speeds. For example, the landing gear assembly shaft can be pushed inwardly by the truck operator to shift to a high speed gear. Rotation of the input shaft by the hand crank will then cause the legs of the assembly to be lowered or raised at a faster rate. This enables the legs of the landing gear assembly to be lowered quickly until they come into engagement with the ground when it is desired to uncouple the trailer from the truck. The gear mechanism of the landing gear assembly is then shifted to a low gear ratio by pulling on the crank, moving the input shaft axially outwardly away from the trailer assembly. When shifted to the low gear ratio, more power is transferred to the legs by the reduced gearing of the gear mechanism. For each rotation of the crank the legs are lowered at a slower rate, but more power is transferred to the legs enabling the landing gear assembly to lift the trailer from the truck when uncoupling the trailer from the truck.
The hand crank of current landing gear assemblies typically has a socket at one end. The crank socket end is positioned axially over the end of the landing gear input shaft when positioning the crank in its operative position to turn the input shaft. A yoke is also formed on the socket end of the crank. The yoke has a pair of arms that project axially outwardly from the socket on opposite sides of the input shaft. Each yoke arm has a slot. A pin extends transversely through the end of the landing gear assembly input shaft and opposite ends of the pin are received in the slots of the crank yoke, thereby attaching the yoke to the gear assembly shaft end.
The pin provides a pivot connection between the landing gear assembly input shaft and the crank that enables the crank to be pivoted upwardly to position the crank socket in alignment with the landing gear assembly input shaft end. The slots in the crank yoke enable the crank to be moved axially toward the trailer to its operative position, inserting the end of the landing gear assembly input shaft into the crank socket while the pin on the end of the input shaft moves through the yoke slots.
The crank is moved to a stored position by manually pulling the crank in an axial direction away from the trailer, removing the landing gear assembly shaft end from the crank socket and causing the shaft pin to move through the yoke slots. This enables the hand crank to be pivoted about the pin through the shaft end to a stored position of the crank beneath the shaft.
Because the gear mechanism of the landing gear assembly is shifted between high and low gear by moving the input shaft axially inwardly toward the gear assembly and axially outwardly away from the gear assembly, shifting the gear assembly often results in the crank socket being unintentionally removed from the landing gear assembly shaft end. For example, with the crank in its operative position on the landing gear assembly shaft end and the shaft pushed axially inwardly, if it is desired to shift the gear ratio the gear assembly shaft must be moved axially outwardly by the hand crank. As a result, the crank socket will disengage from the landing gear shaft when the crank is pulled outwardly to shift gears. This makes it necessary to then push the crank inwardly positioning the socket back over the shaft end, while being careful not to push the landing gear assembly out of the shifted gear while reengaging the crank socket on the shaft end. Thus, the prior art landing gear assemblies are disadvantaged in that shifting the gear assembly by pulling the shaft outwardly often results in the crank being disengaged from the gear assembly input shaft.
A further disadvantage of prior art landing gear assemblies is that the crank is not secured in place to the landing gear input shaft, but is just pushed over the end of the input shaft for the short distance of the shaft end that engages in the crank socket. Only the friction engagement between the shaft end and the interior surface of the crank socket maintains the crank on the landing gear assembly input shaft. There is no positive lock or positive engagement between the crank and the input shaft, and all cranks can come off of the input shaft while the crank is being used to manually turn the shaft, and when the crank is being used to shift the input shaft outwardly when shifting the landing gear assembly.
Prior art landing gear assemblies are also disadvantaged in that the connection of the hand crank to the landing gear assembly input shaft typically has a great deal of clearance between the crank socket and the shaft end and between the crank yoke slots and the shaft pin. This results in the crank being loosely attached to the landing gear shaft end. This loose attachment of the crank allows the crank to wobble as the truck driver is attempting to rotate the landing gear shaft with the crank, which adds to the difficulty of rotating the shaft.